Income Taxes (Details 2) (USD $)	3 Months Ended								12 Months Ended
	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Components of income before taxes
Germany									$ 125,262,000	$ 112,963,000	$ 102,693,000
United States									23,230,000	16,590,000	16,236,000
Other Foreign									49,079,000	48,770,000	40,600,000
Income before taxes	47,217,000	53,649,000	42,412,000	54,293,000	47,473,000	39,909,000	40,460,000	50,481,000	197,571,000	178,323,000	159,529,000
Movement in Valuation Allowances and Reserves [Roll Forward]
Undistributed foreign earnings	409,000,000								409,000,000
Valuation allowance of deferred tax assets
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period				876,000				1,031,000	876,000	1,031,000	2,208,000
Charged to Cost and Expense										0	0
Charged to Other Accounts									2,373,000	116,000
Deductions									0	271,000	1,177,000
Balance at End of Period	$ 3,249,000				$ 876,000				$ 3,249,000	$ 876,000	$ 1,031,000